Process for the oxidation of smooth iron surfaces.



BERARDO GUERINI, OF BBESCIA, ITALY.

rib,

PROCESS FOR THE OXIDATION OF SMOOTH IRON SURFACES.

No Drawing.

have invented certain new and useful Im-.

provements in Processes for the Oxidation of Smooth Iron Surfaces, of which the fol lowing is a specification.

My invention relates to a new method for the superficial oxidation of iron.

Object of my invention is to provide speedily and with a simplicity heretofore unknown, to coat iron objects as gun-barrel tools and the like, with the known superficial layer of oxids that renders them dark bright.

The process consists in preparing a bath containing salts of picric acid. To this end, in a tank containing water, may be introduced some picric acid and some hydrate of sodium or potassium. The rate of such com-' ponents may vary at pleasure, nevertheless for sake of economy may be proceeded as follows: In a suitable tank are admitted 100 parts of water, 8% parts of hydrate of sodium, 16 parts of picric acid, the solution thus formed will contain picrate of sodium and will have a basic reaction. In this solution are dipped the iron or steel objects, while heating is appliedgradually to raise the temperature of the bath to say 130- 150 C. If the iron objects are conveniently smoothed and cleaned, 10 minutes will be sufiicient to obtain the result claimed. The hydrate of sodium contained in the bath Specification of Letters Patent.

Patented an. 25, 1916.

Application filed May 10, 1915. Serial No. 27,095.

forms by reaction with the picric acid in aqueous solution picrate of sodium; the hydrate of sodium being present in excess, by the actionof heat there is developed by reaction between the hydrate of sodium and the picrate of sodium the oxidizing agent which effects superficial oxidation of iron articles dipped in the bath.

Having now particularly described the nature of my invention and in what manner the same should be performed, I claim:

1. A process for oxidation of iron surfaces consisting in the immersion of iron objects in a bath containin sodium picrate and an excess of hydrate 0 sodium.

*2. A process of effecting the surface oxidation of iron or steel consisting in immersing the articles to be treated in a bath containing a, solution of an alkaline picrate and gradually raising the temperature of the bath while the articles are exposed to the action of the same. 4

2. A process for effecting the surface oxidation of iron or steel consisting in immersing the articles to be treated in a bath containing a solution of an alkaline picrate with alkali in excess and gradually raising the temperature of the bath while the articles are exposed to the action of the same.

' In testimony whereof I have'aflixedmy signature in the presence of two witnesses.

Witness LYLE Bone. 

